Scintillator crystal and photomultiplier assemblies with improved emission detection

Abstract

In a general aspect, an apparatus includes a scintillator crystal, and a semiconductor die including a first side and a second side opposite the first side. The semiconductor die includes a photomultiplier array disposed on the first side. The scintillator crystal is disposed on the first side of the semiconductor die. The apparatus also includes a carrier disposed on the second side of the semiconductor die. The photomultiplier array is electrically coupled with the carrier. The apparatus further includes a molding material disposed on a sidewall defined by at least one of the semiconductor die or the carrier. The molding material is configured to protect the photomultiplier array from moisture ingress.

What is claimed is: 
     
         1 . An apparatus, comprising:
 a first photomultiplier having:
 a first side including a first array of photodiodes; and 
 a second side opposite the first side; and 
   a second photomultiplier having:
 a first side including a second array of photodiodes; and 
 a second side opposite the first side, 
   the second side of the first photomultiplier being directly coupled to the second side of the second photomultiplier in a staggered arrangement.   
     
     
         2 . The apparatus of  claim 1 , wherein the second side of the first photomultiplier is soldered to the second side of the second photomultiplier. 
     
     
         3 . The apparatus of  claim 1 , wherein a printed circuit board is excluded from a stack including the first photomultiplier and the second photomultiplier. 
     
     
         4 . The apparatus of  claim 1 , wherein the first photomultiplier includes:
 at least one cathode terminal configured to be connected to external circuitry; and   at least one anode terminal configured to be connected to the external circuitry.   
     
     
         5 . The apparatus of  claim 1 , wherein the first photomultiplier is included in a first wafer and the second photomultiplier is included in a second wafer, the first wafer being wafer bonded to the second wafer. 
     
     
         6 . The apparatus of  claim 1 , further comprising:
 a scintillator crystal coupled with the first side of the first photomultiplier, the apparatus being configured for use in a positron emission tomography (PET) scanner.   
     
     
         7 . The apparatus of  claim 6 , wherein the scintillator crystal is a first scintillator crystal, the apparatus further comprising:
 a second scintillator crystal coupled with the first side of the second photomultiplier.   
     
     
         8 . The apparatus of  claim 1 , wherein:
 the first photomultiplier includes:
 a first plurality of conductive traces disposed on the second side of the first photomultiplier; and 
 a first plurality of through vias respectively electrically coupling a first portion of the first plurality of conductive traces with the first array of photodiodes; and 
   the second photomultiplier includes:
 a second plurality of conductive traces disposed on the second side of the second photomultiplier; and 
 a second plurality of through vias respectively electrically coupling a first portion of the second plurality of conductive traces with the second array of photodiodes. 
   
     
     
         9 . The apparatus of  claim 8 , wherein:
 a second portion of the first plurality of conductive traces are respectively electrically coupled with the first portion of the second plurality of conductive traces; and   a second portion of the second plurality of conductive traces are respectively electrically coupled with the first portion of the first plurality of conductive traces.   
     
     
         10 . The apparatus of  claim 1 , further comprising a flex connector coupled with the first photomultiplier, the flex connector being configured to connect the first photomultiplier with external circuitry. 
     
     
         11 . The apparatus of  claim 1 , wherein:
 the first photomultiplier includes:
 a first semiconductor die including the first array of photodiodes; and 
 a first glass cover disposed on the first array of photodiodes; and 
   the second photomultiplier includes:
 a second semiconductor die including the second array of photodiodes; and 
 a second glass cover disposed on the second array of photodiodes. 
   
     
     
         12 . The apparatus of  claim 1 , wherein the first photomultiplier and the second photomultiplier each exclude a glass cover. 
     
     
         13 . An apparatus comprising:
 a scintillator crystal;   a semiconductor die including a first side and a second side opposite the first side, the semiconductor die including a photomultiplier array disposed on the first side, the scintillator crystal being disposed on the first side of the semiconductor die;   a carrier disposed on the second side of the semiconductor die, the photomultiplier array being electrically coupled with the carrier; and   a molding material disposed on a sidewall defined by at least one of the semiconductor die or the carrier, the molding material configured to protect the photomultiplier array from moisture ingress.   
     
     
         14 . The apparatus of  claim 13 , wherein the carrier is electrically coupled with the photomultiplier array by at least one via that extends through the semiconductor die from the first side of the semiconductor die to the second side of the semiconductor die. 
     
     
         15 . The apparatus of  claim 13 , wherein the carrier is electrically coupled with the photomultiplier array by at least one wire bond encapsulated in the molding material. 
     
     
         16 . The apparatus of  claim 13 , further comprising a flex connector coupled with the carrier, the flex connector being configured to connect the photomultiplier array with external circuitry. 
     
     
         17 . The apparatus of  claim 13 , wherein the molding material includes at least one of epoxy or silicone. 
     
     
         18 . The apparatus of  claim 13 , wherein the molding material extends over at least a portion of the second side of the semiconductor die. 
     
     
         19 . The apparatus of  claim 13 , wherein:
 a perimeter portion of the carrier is partially etched; and   the molding material extends over the partially etched perimeter portion of the carrier.   
     
     
         20 . An apparatus comprising:
 a first semiconductor die including a first photomultiplier array;   a second semiconductor die including a second photomultiplier array, the second semiconductor die being coupled in a stack with the first semiconductor die such that the first photomultiplier array is disposed at a proximal end of the stack and the second photomultiplier array is disposed at a distal end of the stack;   a first scintillator crystal disposed on the first semiconductor die at the proximal end of the stack;   a second scintillator crystal disposed on the second semiconductor die at the distal end of the stack, the stack being disposed between the first scintillator crystal and the second scintillator crystal; and   an encapsulation material disposed:
 on a sidewall defined by the first semiconductor die and the second semiconductor die; and 
 between the first scintillator crystal and the second scintillator crystal. 
   
     
     
         21 . The apparatus of  claim 20 , further comprising:
 a first flex connector coupled with the first semiconductor die, the first flex connector being configured to connect the first photomultiplier array with external circuitry; and   a second flex connector coupled with the second semiconductor die, the second flex connector being configured to connect the second photomultiplier array with the external circuitry.   
     
     
         22 . The apparatus of  claim 20 , wherein the first semiconductor die is directly coupled with second semiconductor die. 
     
     
         23 . The apparatus of  claim 20 , wherein:
 the first scintillator crystal is directly coupled with the first semiconductor die with an optically clear adhesive; and   the second scintillator crystal is directly coupled with the second semiconductor die with the optically clear adhesive.   
     
     
         24 . An apparatus, comprising:
 a scintillator crystal;   a first photomultiplier disposed on a first sidewall of the scintillator crystal;   a second photomultiplier disposed on a second sidewall of the scintillator crystal, the second sidewall being orthogonal to the first sidewall; and   a third photomultiplier disposed on a third sidewall of the scintillator crystal, the third sidewall being parallel to the first sidewall.   
     
     
         25 . The apparatus of  claim 24 , further comprising at least one glass component respectively disposed between at least one of:
 the first photomultiplier and the first sidewall;   the second photomultiplier and the second sidewall; or   the third photomultiplier and the third sidewall.   
     
     
         26 . The apparatus of  claim 24 , wherein the second sidewall is on a side of the scintillator crystal opposite a fourth sidewall of the scintillator crystal configured to receive gamma radiation in a positron emission tomography scanner. 
     
     
         27 . The apparatus of  claim 24 , wherein:
 a first printed circuit board (PCB) is electrically coupled to the first photomultiplier;   a second PCB is electrically coupled to the third photomultiplier; and   the third photomultiplier is electrically coupled to the first PCB via a flex connector.   
     
     
         28 . The apparatus of  claim 24 , further comprising:
 a fourth photomultiplier disposed on a fourth sidewall of the scintillator crystal, the fourth sidewall being orthogonal to the first sidewall, the second sidewall and the third sidewall; and   a fifth photomultiplier disposed on a fifth sidewall of the scintillator crystal, the fifth sidewall being orthogonal to the first sidewall, the second sidewall and the third sidewall, and parallel to the fourth sidewall.   
     
     
         29 . The apparatus of  claim 24 , further comprising:
 a molding material encapsulating at least a portion of the scintillator crystal and being in contact with, at least, respective portions of the first photomultiplier, the second photomultiplier, and the third photomultiplier, such that at least a fourth sidewall of the scintillator crystal is exposed through the molding material.